The last twenty years of brain imaging research has for the first time revealed the functional organization of the human brain in detail. We now know the function and location of dozens of regions of the brain that were not known 20 years ago. Many of these regions are involved in very specific components of cognition, such as the visual perception of color and motion, the visual recognition of faces, places, and bodies, and even high-level mental processes like understanding the meaning of sentence or thinking about what another person is thinking. Yet this tantalizing new map of the human mind and brain raises a pressing, unanswered question: How does all this precise functional organization get wired up in infancy and childhood? When and how does each little patch of cortex take on its distinctive adult function? Is the function of a given cortical region determined by the pre-existing connectivity of that region to the rest of the brain? How plastic is cortical organization in the event of early brain injury? To answer these questions, we will conduct extensive, longitudinal anatomical and functional scanning of children from birth through age 5. This work was not possible until now because it requires several very recent technical advances, including the new ?connectome? scanner at MGH that offers the resolution connectivity maps of the human brain of any scanner in the world, new methods of anatomical imaging in neonates, functional imaging in young infants, and longitudinal registration of brain images from the same person from birth to adulthood. These methods will enable us to test whether the cortical location of each functional region, when scanned at age 4-8, can be predicted from the distinctive connectivity of the same region (registered within subjects across age) at birth. By further including children with focal perinatal strokes, we can test the plasticity of specific cortical regions, versus white matter connections of those regions, in the eventual development of adult functional organization. This work will answer fundamental questions about how the human brain gets wired up over infancy and childhood that are also of great clinical relevance given the high prevalence of neurodevelopmental disorders in which this development goes awry.